This invention relates in general to wellpoints for tapping subterranean liquid levels. More specifically, the invention pertains to a wellpoint employing an outer screen pipe and an inner, vacuum producing intake pipe.
This particular wellpoint configuration has proven highly advantageous. However, the output of such a configuration has been adversely affected when the input of liquid from the screen pipe to the intake pipe has fallen below the capacity of the intake pipe. The intake pipe then draws in free air as well as liquid, resulting in reduced pumping efficiency.
It is, therefore, an object of this invention to provide an improved wellpoint.
It is an additional object of the invention to provide a wellpoint wherein the introduction of free air into the intake pipe is prevented.
It is another object of the invention to improve the pumping efficiency of a wellpoint having an intake pipe and outer screen pipe.
It is another object of the invention to provide a wellpoint including means for selectively reducing the area of screen pipe subjected to vacuum by an intake pipe.